The invention relates to a venetian blind. A venetian blind is a type of window blind, also known as a window shade, for covering a window. Window blinds exist in many forms. In venetian blinds, horizontal slats are provided in a mutually parallel arrangement generally extending in a plane parallel to the plane of the window to be covered. The angle of the slats relative to the plane of the window to be covered can be adjusted to adjust the extent to which light can pass through the cover. Conventionally, venetian blinds typically have flexible ladders in which the slats are suspended between ladder cords or tapes in a succession extending generally parallel to the window plane to be covered, usually in a vertical succession. The orientation of the slats about longitudinal axes thereof is typically controlled by rotating drums and/or pulleys in unison such that the ladder cords or tapes on one side are slightly pulled up at their top ends and ladder cords or tapes on the opposite side are slightly lowered. Thus, the slats are tilted in unison.
For lifting the venetian blind, usually lift cords extend centrally between the ladder cords or tapes through openings in the slats from a bottom beam, via pulleys and cleats in a top beam from which free ends of the lift cords hang down and can be operated by a user to be pull up the venetian blind to a lifted configuration allowing essentially free view and light passage through the window or to lower the venetian blind to a lowered position covering the window, but allowing more or less vision and light passage through the venetian blind, depending on the orientation of the slats. When the lift cords are pulled, the bottom beam of the blind moves upward entrains the lowest slat and successively each next slat on top of the entrained one, which can be continued until all slats are tightly stacked against the upper beam of the blind.
Venetian blinds can to some extent shield the interior of a building from heat or cold, reduce the influx of light to varying degrees and provide privacy by preventing shielding an interior behind the blind from being visible from the outside.
A disadvantage of conventional venetian blinds is that all slats are always in the same orientation. While this is desirable from the point of view of obtaining a uniform structure throughout the effective surface of the venetian blind, it does not allow to combine for instance a tilted positions of slats in a lower or central portion of the venetian blind, for instance for privacy and/or shielding plants from direct sun light, with a horizontal orientation of slats in an upper portion of the venetian blind allowing a to a large extent free entry of daylight through that upper portion. Generally, blocking light passage through an upper portion while allowing free view (out) through a lower portion is in principle possible by partially lifting the venetian blind, but this results in a completely uncovered lower portion of the window and a visually less attractive configuration with the lower beam extending more or less centrally across the window.